* Planning is everything *

Plan ahead. Make sure you've got the most important things at hand or within reach before you embark on this addicting hobby. These things are (in no particular order):

Cash
As you'll quickly find out, this new hobby requires a hefty wallet. Choose cash, not credit.

Understanding
Know what you want from a tuned car, what to expect from your mods, and what you're getting yourself into if you decide to do the work yourself.

Tools
The right tool for the job - be it a torque wrench, lift or your local tuning expert.

Time
Give yourself ample time to do the work or to be without your car. If you decide to tackle a job you've never done before, give yourself lots of extra time.

A Plan
Know your goals so that you know when you've achieved them. Stage your tuning. This not only helps you to make educated modifications, but is also easier on your pocketbook.